Files
wasmtime/examples/multi.rs
Alex Crichton afd980b4f6 Refactor the internals of Func to remove layers of indirection (#1363)
* Remove `WrappedCallable` indirection

At this point `Func` has evolved quite a bit since inception and the
`WrappedCallable` trait I don't believe is needed any longer. This
should help clean up a few entry points by having fewer traits in play.

* Remove the `Callable` trait

This commit removes the `wasmtime::Callable` trait, changing the
signature of `Func::new` to take an appropriately typed `Fn`.
Additionally the function now always takes `&Caller` like `Func::wrap`
optionally can, to empower `Func::new` to have the same capabilities of
`Func::wrap`.

* Add a test for an already-fixed issue

Closes #849

* rustfmt

* Update more locations for `Callable`

* rustfmt

* Remove a stray leading borrow

* Review feedback

* Remove unneeded `wasmtime_call_trampoline` shim
2020-03-19 14:21:45 -05:00

95 lines
2.8 KiB
Rust

//! This is an example of working with mulit-value modules and dealing with
//! multi-value functions.
//!
//! Note that the `Func::wrap*` interfaces cannot be used to return multiple
//! values just yet, so we need to use the more dynamic `Func::new` and
//! `Func::call` methods.
// You can execute this example with `cargo run --example multi`
use anyhow::{format_err, Result};
use wasmtime::*;
fn main() -> Result<()> {
// Configure our `Store`, but be sure to use a `Config` that enables the
// wasm multi-value feature since it's not stable yet.
println!("Initializing...");
let engine = Engine::new(Config::new().wasm_multi_value(true));
let store = Store::new(&engine);
// Compile.
println!("Compiling module...");
let module = Module::from_file(&store, "examples/multi.wat")?;
// Create external print functions.
println!("Creating callback...");
let callback_type = FuncType::new(
Box::new([ValType::I32, ValType::I64]),
Box::new([ValType::I64, ValType::I32]),
);
let callback_func = Func::new(&store, callback_type, |_, args, results| {
println!("Calling back...");
println!("> {} {}", args[0].unwrap_i32(), args[1].unwrap_i64());
results[0] = Val::I64(args[1].unwrap_i64() + 1);
results[1] = Val::I32(args[0].unwrap_i32() + 1);
Ok(())
});
// Instantiate.
println!("Instantiating module...");
let instance = Instance::new(&module, &[callback_func.into()])?;
// Extract exports.
println!("Extracting export...");
let g = instance
.get_export("g")
.and_then(|e| e.func())
.ok_or(format_err!("failed to find export `g`"))?;
// Call `$g`.
println!("Calling export \"g\"...");
let results = g.call(&[Val::I32(1), Val::I64(3)])?;
println!("Printing result...");
println!("> {} {}", results[0].unwrap_i64(), results[1].unwrap_i32());
assert_eq!(results[0].unwrap_i64(), 4);
assert_eq!(results[1].unwrap_i32(), 2);
// Call `$round_trip_many`.
println!("Calling export \"round_trip_many\"...");
let round_trip_many = instance
.get_export("round_trip_many")
.and_then(|e| e.func())
.ok_or(format_err!("failed to find export `round_trip_many`"))?;
let args = vec![
Val::I64(0),
Val::I64(1),
Val::I64(2),
Val::I64(3),
Val::I64(4),
Val::I64(5),
Val::I64(6),
Val::I64(7),
Val::I64(8),
Val::I64(9),
];
let results = round_trip_many.call(&args)?;
println!("Printing result...");
print!(">");
for r in results.iter() {
print!(" {}", r.unwrap_i64());
}
println!();
assert_eq!(results.len(), 10);
assert!(args
.iter()
.zip(results.iter())
.all(|(a, r)| a.i64() == r.i64()));
Ok(())
}